Anterior approach to the lumbar spine

hi my name is zach deteren i'm one of the spine fellows at seattle science foundation completed my neurosurgery residency in canada and i'm here for a year to do a spine fellowship here to show you an immensely interesting dissection um that you will probably never get to see um that has taken the better part of two weeks to complete so this is a human thorax with the organs taken out revealing a human vertebral body spinal canal from the front so this is the top this is the bottom this is the left this is the right um this is where the chest was so we took off the ribs took out the heart took out the lungs these are the backs of your ribs um and this is your spine down the middle this is where your ribs end this is your 12th and final rib and the goal of this dissection was to in a detailed manner examine something called your lumbar plexus which is the nerves that come out from t12 to l5 and supply the muscles and sensation to your legs so these are the bones the dark part of the bones the white parts are the discs so it's bone disc bone disc bone disc bone disc this is your last rib so this is t12 l1 l2 l3 l4 l5 on this side we just kind of did a minimal dissection and on this side i totally totally skeletonized the lumbar plexus and just because it's very very interesting and you never get to see this view i then came with a straight saw and took off the connections between the front bones and the backbones of your spinal column and disconnected the front to give us an anterior view of the lumbar spine which you don't typically get to see so that big reveal is the bone taken off this is l1 l2 l3 l4 i left l5 on just because it was at a a precarious angle and they didn't want to risk damaging any of these nerves that i've dissected these are actually not yellow normally i painted them yellow which was no trivial task it was like painting wet spaghetti so it was like a water-based paint pen it's kind of interesting because you never separate just the vertebral bodies and you can see there's a little bit of give to it um but not too much uh you can see the the discs kind of compressing and expanding is kind of interesting it's not something you typically get to see and so this is called your dura and it's the outer layer of your spine and i made an incision down the middle and when i reflect that to the sides like that you can see the actual nerves themselves which just kind of look like looks like a bag of wet spaghetti noodles so your spinal cord typically ends in something called your conus medullaris which in most people ends from t12 to l2 somewhere and that is up there and then the rest of your spinal canal from your conus and below is something called your cauda equina which means horse's tail in latin and you can see it's just a fine array of nerves um so this is an anterior view of your cauda equina which is not something you typically get to see and these bones that i cut off to separate the front bones um those are called your pedicles and they're the bones that connect the back to the front so we saw it across those and as you can see from these yellow painted nerves and the nerve roots on this side nerve roots come out right beneath the pedicle at each level and then they form this intertwined mesh of nerves that forms your lumbar plexus so you've got these wet spaghetti noodles that pierce the dura and are come out in sheathed in nerve root dura and then go out and supply various sensory and motor aspects of your abdomen and lower extremities and pelvic area so just going through the nerves real quickly um that i've exposed this is your t12 so if this is your t12 vertebral body then this is your t12 nerve root and this probably forms your subcostal nerve kind of self-explanatory subcostal under the rib this would be your l1 and everyone's lumbar plexus is very there's pictures of it you can find pictures of it but it actually always looks different in real life and there's a lot of variability and a lot of variance in between humans so this is your l1 and l1 typically composes of your iliohypogastric nerve and your ilio inguinal nerve probably that one actually um and then this is probably the genito femoral nerve which typically has aspects of your l1 nerve root and your l2 nerve root but there's variations between people but this looks like your genital femoral nerve so that's l1 l2 these are probably going towards the lateral femoral cutaneous nerve of your thigh which is mainly a sensory nerve um so this is l3 um and kind of the biggest nerve here uh this one that you see here is most likely your femoral nerve um which is the biggest nerve that arrives from the lumbar part of this plexus your sciatic nerve is actually bigger but that forms lower down and pretty much the reason that we're doing this project is to put the bone back on um there we go we took this uh body before before starting the dissection and we put it through a very high caliber magnet in a 3t mri machine with a very specific radiographic protocol we then analyzed it and we have a company that made a 3d print out of of the lumbar plexus and the reason we did that is because we wanted to see if the anatomy from a 3d printout correlated with the actual anatomy that we saw in a meticulous dissection and the reason we do that is because there are various various surgical approaches that we want to approach the spine from the sides it's a lateral approach to the lumbar spine and i've as you can see there's still muscle over here on this side but on this side in order to get an actual very nice skeletonized dissection i had to core out all of the muscle just to expose the nerves themselves but in reality these nerves run through a muscle called your psoas muscle which attaches to the anterior part of your spine and fans out downwards and the actual orientation of these nerves would be more instead of laying down and backwards like they are here with gravity they normally run through the muscle and come up and forwards so if you can imagine these nerves coming up this way if we want to approach the spine from the sides we want to avoid hitting these nerves most importantly probably your femoral nerve because if you hit that nerve or damage that nerve during this approach it can result in dramatic leg weakness that typically doesn't improve so essentially we're seeing if it would be feasible or reasonable to do a high resolution three t 3d printed mri in patients who are undergoing a lateral approach to the spine in an effort to kind of pick a pathway that would minimize the risk of of encountering or damaging these nerves a standard surgery that you would do from a lateral approach would be something that would go through that psoas muscle is something called an x-lift an extreme lateral inter-body fusion and in that you go through the sides here's the disc here you would take out that disc with surgical tools and then put in a titanium cage filled with material conducive for bony fusion and you would replace that disc with that cage in an effort to get these two bones to fuse um so that's an x lift where you go through the psoas muscle you go through this muscle to get to there there's also something called an oblique lateral interbody fusion an olive in which you go a little bit more anteriorly and go in front of the muscle which does avoid all these nerves if you were to go from a slightly more anterior oblique approach but if you do it from that approach you run the risk of damaging visceral organs like your ureter or other abdominal organs um so we're we're investigating this from an x-lift perspective um so pretty interesting view that you don't normally get to see other things to show this little tendril that i'm reaching down here is probably called this is most likely i can feel that it's very tethered down here it's called your phylum terminal which is kind of the end point of all of these nerves it's kind of the most caudal aspects of the intrathecal portion of this um it's just it's kind of interesting to note how whereas in a textbook these are almost cartoon-like and very well-defined there's a lot of interconnections and fibrous web-like connections between all of these nerves that you don't typically see in a textbook kind of just illustrating how precarious this approach of going through this muscle is where all these nerves are harbored there you have it anterior approach to the lumbar spine dissection of the lumbar plexus intrathecal view of the cauda equina and conus medullaris

Channel: Seattle Science Foundation

Views: 244,061

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Keywords: Seattle Science Foundation, Health, Medicine, #ssf, anatomy, surgical videos, spine surgery, surgical demonstration, orthopedic surgery, medical education, continuing medical education, neurosurgery, cranial surgery, live surgery, bioskills lab, medical student, plastic surgery, brain tumor surgery, surgery, brain surgery, brain, spine, knee, hip, brain surgery for epilepsy, sinus surgery, human heart, lumbar puncture, brain operation, dissection, seattle science foundation

Id: lrNJZsvGoSw

Length: 13min 3sec (783 seconds)

Published: Mon Mar 22 2021